The relative decrease change. Definition:
The relative decrease change is the difference in an indicator over two periods in time, v1 - v2, relative to the value of the indicator in the earlier period, v1.
- Where:
- v1 - is called the reference value (original, initial number);
- v2 - is called the new value (the end value).
- In our case: v1 = 23, v2 = - 8.9.
The relative decrease change. Formula:
The relative decrease change =
The actual change / |v1|
(v1 - v2) / |v1| =
- Legend:
- v1 - the original number
- |v1| - the positive value of v1, |v1| >= 0. By example: |10| = 10; |-10| = 10.
- v2 - the new value
- The actual change = v1 - v2
- / - the fraction bar (division)
Why do we use |v1| in the formula instead of v1?
- Let's see what happens if we use v1 instead of |v1|:
- Choose a random negative number as the initial value: - 53.
- Choose a random positive number for the end value: 76.
Formula and calculation:
(v1 - v2) / v1 =
(- 53 - 76) / - 53 =
-129 / - 53 ≈
2.433962264151 ≈
2.43
Although the absolute difference is negative: -129, the relative decrease change is positive: 2.43. By using |v1| instead of v1, the error is corrected.
The relative percent decrease change. Detailed calculations below
By multiplying a number by the fraction 100/100,
we change only the form of the result, not the result.
- 100/100 = 100% = 100 ÷ 100 = 1.
- n × 100/100 = (n × 100)/100 = (n × 100)%, any number.
The relative percent decrease change. Formula:
The relative percent decrease change =
The relative decrease change × 100/100 =
(The relative decrease change × 100)/100 =
(The relative decrease change × 100)%
Calculate the relative percent decrease change:
(23 - (- 8.9))/|23| =
(23 + 8.9)/|23| =
31.9/23 =
31.9 ÷ 23 =
31.9 ÷ 23 × 100/100 =
(31.9 × 100 ÷ 23)/100 =
(3,190 ÷ 23)/100 =
138.695652173913/100 =
138.695652173913% ≈
138.7%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 23 to the final, end value - 8.9:
Not rounded = 138.695652173913%
Rounded off to max. 2 decimal places ≈ 138.7%
The absolute (actual) difference
23 + 8.9 = 31.9
By what percentage has 23 decreased?
Answer: By ≈ 138.7%
By what percentage is - 8.9 smaller than 23?
Answer: By ≈ 138.7%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).